States of Matter, Particle Theory, and Chemical Changes

State of matter

The physical form a substance exists in (solid, liquid, gas)

Solid

State where particles are tightly packed and vibrate in fixed positions

Liquid

State where particles are close together but can slide past each other

Gas

State where particles are far apart and move freely

Particle theory

All matter is made of tiny particles in constant motion

Melting

Change of state from solid to liquid due to heat

Freezing

Change of state from liquid to solid due to loss of heat

Evaporation

Change from liquid to gas below boiling point

Boiling

Rapid evaporation at a fixed temperature

Diffusion

Movement of particles from high to low concentration

Element

A substance made of only one type of atom

Atom

The smallest particle of an element

Simple substance

An element that exists on its own

Compound

Two or more elements chemically bonded together

Chemical bond

Force holding atoms together in a compound

Mixture

Two or more substances mixed but not chemically bonded

Physical separation

Separation without chemical change

Chemical formula

Shows types and numbers of atoms in a substance

Fixed ratio

Elements in a compound are always combined in the same ratio

Air

A mixture of gases

Solution

A solute dissolved in a solvent

Solute

Substance that dissolves

Solvent

Substance that dissolves the solute

Aqueous solution

Solution where water is the solvent

Dilute solution

small amount of solute in a large amount of solvent.

Concentrated solution

large amount of solute in a small amount of solvent

Saturated solution

Solution that cannot dissolve more solute at a given temperature

Crystallisation

Formation of solid crystals from a solution

Solubility

Amount of solute that dissolves at a given temperature

Solubility curve

Graph showing solubility at different temperatures

Filtration

Separation of an insoluble solid from a liquid

Residue

Solid left on the filter paper

Filtrate

Liquid that passes through the filter paper

Distillation

Separation of a liquid from a solution by boiling and condensing

Liebig Condenser

Apparatus that cools vapour into liquid

Condensation

Change of state from gas to liquid

Chromatography

Separation based on solubility and attraction to paper

Solvent front

Distance travelled by solvent in chromatography

Pigment

Coloured substance in dyes or inks

Acid

PH less than 7 and turns litmus paper red

Base

Substance with PH higher than 7 and turn s blue in litmus paper

Alkali

A base that dissolves in water

pH scale

Scale from 0-14 measuring how acidic or basic a substance is

Indicator

Substance that changes colour depending on pH

Litmus

Indicator that turns red in acid and blue in base

Universal indicator

Indicator showing full pH range by colour

Neutral

Neither acidic nor basic (pH 7)

Neutralisation

Reaction between an acid and a base

Salt and water

Product formed from neutralisation

Chemical reaction

Process where new substances are formed

Reactant

Substance used up in a reaction

Product

Substance formed in a reaction

Physical change

Change with no new substance formed

Chemical change

Change where new substances are formed

Word equation

Equation written using names of substances

Chemical equation

Equation written using symbols and formulas

Balanced equation

Equation with equal atoms on both sides

Law of conservation of mass

Mass is neither created nor destroyed

Particle theory explanation

Atoms rearrange but are not lost or gained

Rate of reaction

Speed at which reactants turn into products

Collision theory

Reactions occur when particles collide with enough energy

Temperature

Higher temperature increases reaction rate

Surface area

Larger surface area increases reaction rate

Catalyst

Substance that speeds up reaction without being used

Neutralisation reaction

Acid + base → salt + water

Examples of acids

Sulfuric, Hydrochloric, Citric acids

Examples of bases

Sodium Hydroxide, Baking Soda

Salt solution

Product dissolved in water after neutralisation

Acid rain

Rain made acidic by pollution gases

Exothermic reaction

Reaction that releases heat

Endothermic reaction

Reaction that absorbs heat

Activation energy

Minimum energy needed to start a reaction

Energy profile diagram

Graph showing energy changes in a reaction

Bond energy

Energy needed to break chemical bonds

Nucleus

Centre of atom containing protons and neutrons

Proton

Positively charged particle

Neutron

Particle with no charge

Electron

Negatively charged particle

Atomic number

Number of protons in an atom

Mass number

Protons plus neutrons

Electron shell

Energy level around nucleus

Bohr model

Model showing electrons in shells

First 20 elements

Elements commonly examined at JC

Periodic Table

Arrangement of elements by atomic number

Group

Vertical column in the Periodic Table

Period

Horizontal row in the Periodic Table

Valence electrons

Electrons in outer shell

Ionic compound

Compound formed by electron transfer

Covalent compound

Compound formed by sharing electrons

Subscript

Small number showing atom count

Charge balance

Total positive equals total negative charge

Predicting formulas

Using valence electrons

Metal

Element that conducts heat and electricity

Non‑metal

Element that does not conduct well

Alloy

Mixture of metals

Corrosion

Slow destruction of metal by reaction

Rusting

Corrosion of iron

Sustainability

Meeting needs without harming future generations

Three pillars

Environmental, social, economic

Fossil fuels

Coal, oil and gas